.watermark {
    position: fixed;
    width: 100vw;
    height: 100vh;
    background: url('../images/shuiyin.png');
    top: 0;
    background-size: 100%;
    z-index: 1;
    max-width: 750px;
    margin: 0 auto;
    pointer-events: none;
    /*解决上层加了水印出发不到下层的点击事件*/
}